Table of Contents

Raspberry Pi Pico (RP2040) pin out

The Raspberry Pi Pico has 40 pins, with 26 user-accessible GPIO pins (GP0–GP22, GP26–GP28). GPIO numbering in .NET nanoFramework matches the RP2040 GP numbers directly — GpioPin pin = gpio.OpenPin(25) opens GP25.

The official pinout diagrams are available from Raspberry Pi:

Full pin table

Physical Pin GPIO Primary function SPI I2C UART PWM ADC
1 GP0 GPIO SPI0 RX I2C0 SDA UART0 TX PWM0 A
2 GP1 GPIO SPI0 CSn I2C0 SCL UART0 RX PWM0 B
3 GND Ground
4 GP2 GPIO SPI0 SCK I2C1 SDA UART0 CTS PWM1 A
5 GP3 GPIO SPI0 TX I2C1 SCL UART0 RTS PWM1 B
6 GP4 GPIO SPI0 RX I2C0 SDA UART1 TX PWM2 A
7 GP5 GPIO SPI0 CSn I2C0 SCL UART1 RX PWM2 B
8 GND Ground
9 GP6 GPIO SPI0 SCK I2C1 SDA UART1 CTS PWM3 A
10 GP7 GPIO SPI0 TX I2C1 SCL UART1 RTS PWM3 B
11 GP8 GPIO SPI1 RX I2C0 SDA UART1 TX PWM4 A
12 GP9 GPIO SPI1 CSn I2C0 SCL UART1 RX PWM4 B
13 GND Ground
14 GP10 GPIO SPI1 SCK I2C1 SDA UART1 CTS PWM5 A
15 GP11 GPIO SPI1 TX I2C1 SCL UART1 RTS PWM5 B
16 GP12 GPIO SPI1 RX I2C0 SDA UART0 TX PWM6 A
17 GP13 GPIO SPI1 CSn I2C0 SCL UART0 RX PWM6 B
18 GND Ground
19 GP14 GPIO SPI1 SCK I2C1 SDA UART0 CTS PWM7 A
20 GP15 GPIO SPI1 TX I2C1 SCL UART0 RTS PWM7 B
21 GP16 GPIO SPI0 RX I2C0 SDA UART0 TX PWM0 A
22 GP17 GPIO SPI0 CSn I2C0 SCL UART0 RX PWM0 B
23 GND Ground
24 GP18 GPIO SPI0 SCK I2C1 SDA UART0 CTS PWM1 A
25 GP19 GPIO SPI0 TX I2C1 SCL UART0 RTS PWM1 B
26 GP20 GPIO SPI0 RX I2C0 SDA UART1 TX PWM2 A
27 GP21 GPIO SPI0 CSn I2C0 SCL UART1 RX PWM2 B
28 GND Ground
29 GP22 GPIO SPI0 SCK I2C1 SDA UART1 CTS PWM3 A
30 RUN Reset
31 GP26 GPIO/ADC SPI1 SCK I2C1 SDA UART1 CTS PWM5 A ADC0
32 GP27 GPIO/ADC SPI1 TX I2C1 SCL UART1 RTS PWM5 B ADC1
33 AGND Analogue ground
34 GP28 GPIO/ADC SPI1 RX I2C0 SDA UART0 TX PWM6 A ADC2
35 ADC_VREF ADC reference voltage
36 3V3(OUT) 3.3 V regulated output
37 3V3_EN 3.3 V enable (pull low to disable)
38 GND Ground
39 VSYS 2 V – 5 V system input
40 VBUS 5 V USB input

[!Note]: GP23, GP24, GP25 and GP29 are used internally on the Pico board:

  • GP23 — controls the on-board SMPS power save mode
  • GP24 — VBUS sense (USB power detection) on Pico; used by the CYW43439 wireless chip on Pico W
  • GP25 — on-board LED on Pico (on Pico W this LED is connected through the wireless chip)
  • GP29 — used for ADC to monitor VSYS / 3 (internal measurement)

On-board LED

Board LED GPIO Notes
Pico / Pico H GP25 Direct GPIO output
Pico W / Pico WH WL_GPIO0 Driven via CYW43439 wireless chip; not accessible as a standard GPIO

ADC

The RP2040 has a 12-bit ADC with 4 inputs available (3 external + 1 internal temperature sensor).

ADC channel GPIO Notes
ADC0 GP26 Pin 31
ADC1 GP27 Pin 32
ADC2 GP28 Pin 34
ADC3 — Internal temperature sensor

ADC input voltage range is 0 V to 3.3 V. Do not exceed 3.3 V on ADC pins.

PWM

The RP2040 has 8 PWM slices, each with two channels (A and B), giving 16 independent PWM outputs total. Almost every GPIO pin can be connected to a PWM channel. Pins on the same PWM slice share the same frequency.

PWM Channel A Channel B
Slice 0 GP0, GP16 GP1, GP17
Slice 1 GP2, GP18 GP3, GP19
Slice 2 GP4, GP20 GP5, GP21
Slice 3 GP6, GP22 GP7
Slice 4 GP8 GP9
Slice 5 GP10, GP26 GP11, GP27
Slice 6 GP12, GP28 GP13
Slice 7 GP14 GP15

SPI default mapping

The RP2040 has two SPI controllers. The nanoFramework target uses the following default pin mapping:

Bus Clock (SCK) MOSI (TX) MISO (RX) Chip Select (CSn)
SPI0 GP18 GP19 GP16 GP17
SPI1 GP10 GP11 GP8 GP9

These defaults can vary by target build. Refer to the nf-interpreter target source for the exact configuration.

I2C default mapping

The RP2040 has two I2C controllers. The nanoFramework target uses the following default pin mapping:

Bus SDA SCL
I2C0 GP4 GP5
I2C1 GP6 GP7

UART default mapping

The RP2040 has two UART controllers.

Port TX RX
UART0 GP0 GP1
UART1 GP4 GP5

Note: UART support is not yet included in the nanoFramework firmware for RP2040. Check the nf-interpreter repository for updates.

Pico W — wireless chip pin sharing

On the Pico W, the CYW43439 wireless chip uses an SPI interface to the RP2040. The following RP2040 pins are shared with the wireless subsystem and are not available as user GPIO on Pico W:

RP2040 GPIO Usage on Pico W
GP23 Wireless power save control
GP24 Wireless interrupt / data
GP25 Wireless SPI data / chip-enable
GP29 Wireless SPI clock / VSYS voltage monitor
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